From e56dfd967ce460481a9922d14e931b438548093d Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Mon, 11 Nov 2019 14:43:42 +1100
Subject: handle s being updated without len being updated

fix #17279
---
 numeric.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'numeric.c')

diff --git a/numeric.c b/numeric.c
index f5fc1f634a..2b880376bd 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1560,7 +1560,7 @@ Perl_my_atof3(pTHX_ const char* orig, NV* value, const STRLEN len)
         /* strtold() accepts 0x-prefixed hex and in POSIX implementations,
            0b-prefixed binary numbers, which is backward incompatible
         */
-        if ((len == 0 || len >= 2) && *s == '0' &&
+        if ((len == 0 || len - (s-orig) >= 2) && *s == '0' &&
             (isALPHA_FOLD_EQ(s[1], 'x') || isALPHA_FOLD_EQ(s[1], 'b'))) {
             *value = 0;
             return (char *)s+1;
-- 
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